SkCrabbyAvifCodec: Support subsets

Add support in SkCrabbyAvifCodec for decoding subsets of an
image. It takes the same path as images with crop rectangle
specified.

Change-Id: I2d87725ae7572f3bba1957b3cb31f59274530bc7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/938239
Auto-Submit: Vignesh Venkat <vigneshv@google.com>
Commit-Queue: Vignesh Venkat <vigneshv@google.com>
Reviewed-by: Jorge Betancourt <jmbetancourt@google.com>
Commit-Queue: Jorge Betancourt <jmbetancourt@google.com>
2 files changed